Conventional bi-fuel injection systems for internal combustion engines require separate fuel systems and fuel management hardware on the engine for each fuel employed. The additional components increase costs and consume valuable space within the engine compartment. For example, if gasoline and liquified petroleum gas (LPG) are the fuels selected to operate an engine, the engine would include a fuel injection system for the gasoline and separate fuel injection system for delivering the LPG. Furthermore, in a typical bi-fuel system, when the LPG system supplies fuel, no fuel is flowing through the gasoline injectors and when the gasoline system supplies fuel, no fuel is flowing through the LPG system. Stagnant fuel, in the system which is not supplying fuel, is exposed to elevated temperature for long periods of time which can aggravate deposit formation in the inactive injectors and thus, negatively affect emissions.
Accordingly, a need exists to provide a bi-fuel injection system which requires a single fuel rail and fuel injectors capable of receiving either fuel such that one of the fuels is continuously flowing through the injectors during operation of the engine, and which purges residual fuel when switching from one fuel to the other.